1. Field Of The Invention
This invention relates to an improved fuse ejector and, more particularly, to a fuse ejector and injector for cartridge type fuses.
2. Description Of The Prior Art
Many different types of devices have been proposed in the prior art for inserting cartridge type fuses into and/or ejecting such fuses from conventional fuse retaining spring clips mounted in a fixed spaced apart relationship on a fuse support, such as a printed circuit, or PC, board. One such known device employes a "dedicated" plastic tool having finger gripping portions at one end and a C-shaped fuse holder configuration at its other end. Such a tool must first have its C-shaped end forced over an end of the unmounted fuse and subsequently positioned on a center portion of the fuse. The fuse may then be mounted in the customary manner in the spaced spring clips by gripping the tool at the finger gripping portions and forcing the ends of the fuse into a support relationship with the spring clips. In order to remove the installed fuse from its supporting clips, a fuse removing force may be applied by grasping the tool at the finger portions and pulling against the restraining force of the clips until the fuse is free of the clips. Such a tool is, at best, inconvenient to use. Additionally, because of slippage between the tool and the body of the fuse, difficulty has been experienced in inserting the fuse properly between the spaced clip contacts.
The use of unshrouded or unprotected fuse holders, or clips, poses a shock hazard for one servicing equipment employing such exposed fuse holders either when a fuse is inserted or removed or in the event of accidental contact during a servicing operation because of the exposed electrically "live" surfaces of the fuse clips.
In order to prevent such a shock hazard, it has been proposed in the prior art to provide a protective shroud around the fuse clips in the form of an electrically non-conductive U-shaped shell having its base portion mounted rigidly on the associated fuse mounting support. The sides of the shell are arranged to surround the fuse and the spring clips and to extend generally perpendicularly away from the shell base to a height coextensive with the spring clips. Centrally located open slots formed in the sides of the shell enable the fuse to be grasped by the central portion of the fuse when it is desired to insert or remove a fuse from the spring clip contacts.
While such a shroud provides a measure of protection from accidental contact with the fuse clips there is still the possibility that the fuse will be damaged by a mechanical tool such as a screwdriver which is often used in lieu of a proper tool, to force the fuse into or out of its clip engaging position. Since a significant force is required to remove cartridge type fuses from the clips retaining them, the fuses sometimes unexpectedly pop out of the fuse clips and fly into the face of the person employing an improper tool such as a screwdriver to remove them.
There are other prior art fuse pullers in the form of electrically insulating pliers which are employed to grip the fuse and to remove or to insert it with respect to the clips. The inherent problem with such devices is that the tool must be handy when it is desired to change fuses and adequate clearance must be provided for manuvering the tool in the vicinity of the fuse.
A combined fuse shroud and puller, or ejector, is shown in U.S. Pat. No. 3,896,408 which is assigned to the same assignee as the present application. The structure of this puller includes an open top, electrically insulating receptacle surrounding the fuse and the spring clips. The bottom of the receptacle has two openings through which the fuse clips can protrude. A pedestal is attached to the outside surface of the bottom of the receptacle and is arranged to pass through a hole in a mounting board. The free end of the pedestal is provided with a pair of ears to inhibit complete withdrawal of the pedestal from the hole. The inside surface of the bottom of the receptacle is provided with ramp surface sloping away from the inside surface toward one of the fuse clips. When the shroud is moved away from the mounting board to the extend permited by the ears on the pedestal, the ramp surface bears against the fuse and forces it out of one of the spring clips. The fuse can then be extracted from the shroud and the remaining fuse clip. However, the subsequent extraction from the remaining spring clip is difficult to perform within the confines of the shroud. Further, the clips and fuse ends are still exposed through the open top of the shroud which affords the possibility of accidental contact therewith. Finally, the insertion of a replacement fuse is not assisted by this fuse puller and is achieved only by a manual handling of the fuse within the shroud body which operation could pose a shock hazard if the fuse clips have been left electrically "live".
Accordingly, it is an object of the present invention to provide a fuse puller that eliminates the possibility of a shock hazard while expediting the removal and/or insertion of a fuse in the fuse support clips.